Two-dimensional self-aligned super via integration on self-aligned gate contact

ABSTRACT

Techniques relate to contacts for semiconductors. First gate contacts are formed on top of first gates, second gate contacts are on second gates, and terminal contacts are on silicide contacts. First gate contacts and terminal contacts are recessed to form a metal layer on top. Second gate contacts are recessed to be separately on each of the second gates. Filling material is formed on top of the recessed second gate contacts and metal layer. An upper layer is on top of the filling material. First metal vias are formed through filling and upper layers down to metal layer over first gate contacts. Second metal vias are formed through filling and upper layers down to metal layer over terminal contacts. Third metal vias are formed through filling and upper layers down to recessed second gate contacts over second gates. Third metal vias are taller than first.

BACKGROUND

The present invention relates generally to integrated circuits, and morespecifically, to providing a scheme on how to integrate two-dimensionalself-aligned super via (tall via) (V0) on self-aligned gate contactmetal layer.

The back end of line (BEOL) is the second portion of integrated circuitfabrication where the individual devices (transistors, capacitors,resistors, etc.) are interconnected with wiring on the wafer, i.e., themetallization layer. Common metals are copper interconnect and aluminuminterconnect. BEOL generally begins when the first layer of metal isdeposited on the wafer. BEOL includes contacts, insulating layers(dielectrics), metal levels, and bonding sites for chip-to-packageconnections.

General steps of BEOL may include silicidation of source/drain regionusually considered as front end of line (FEOL) or middle of line (MOL).BEOL usually starts from material when copper (Cu) is used.

SUMMARY

According to one or more embodiments, a method of forming contacts for asemiconductor device. The method includes forming first gate contacts ontop of first gates, second gate contacts on top of second gates, andterminal contacts on top of trench silicide contacts, where the trenchsilicide contacts are individually formed on top of sources and drains.Also, the method includes recessing the first gate contacts and theterminal contacts in order to form a metal layer on top of the firstgate contacts and the terminal contacts, and recessing the second gatecontacts such that recessed second gate contacts are separately on topof each of the second gates, where each of the recessed second gatecontacts are separated from one another by a dielectric layer. Also, themethod includes forming a filling material on top of the recessed secondgate contacts and the metal layer and forming an upper layer on top ofthe filling material. The method includes forming first metal vias ontop of the metal layer over the first gate contacts, according to afirst via pattern through the filling material and the upper layer downto the metal layer on top of the first gate contacts. Further, themethod includes forming second metal vias on top of the metal layer overthe terminal contacts, according to a second via pattern through thefilling material and the upper layer down to the metal layer on top ofthe terminal contacts. The method includes forming third metal vias ontop of the recessed second gate contacts over the second gates,according to a third via pattern through the filling material and theupper layer down to the recessed second gate contacts. The third metalvias are taller than the first metal vias.

According to one or more embodiments, a method of forming contacts for asemiconductor device is provided. The method includes forming gatecontacts on top of gates and recessing the gate contacts such thatrecessed gate contacts are separately on top of each of the gates. Eachof the recessed gate contacts are separated from one another by adielectric layer. The method includes forming a filling material on topof the recessed gate contacts and forming an upper layer on top of thefilling material. Also, the method includes forming metal vias on top ofthe recessed gate contacts over the gates, according to a via patternthrough the filling material and the upper layer down to the recessedgate contacts.

According to one or more embodiments, a semiconductor device isprovided. The semiconductor device includes first gate contacts on topof first gates, second gate contacts on top of second gates, andterminal contacts on top of trench silicide contacts, where the trenchsilicide contacts are individually formed on top of sources and drains.The semiconductor device includes a metal layer on top of the first gatecontacts and the terminal contacts, where the second gate contacts arerecessed such that recessed second gate contacts are separately on topof each of the second gates, wherein each of the recessed second gatecontacts are separated from one another by a dielectric layer. Also, thesemiconductor device includes a filling material on top of the recessedsecond gate contacts and the metal layer, and an upper layer is on topof the filling material. First metal vias are formed on top of the metallayer over the first gate contacts, according to a first via patternthrough the filling material and the upper layer down to the metal layeron top of the first gate contacts. Second metal vias are formed on topof the metal layer over the terminal contacts, according to a second viapattern through the filling material and the upper layer down to themetal layer on top of the terminal contacts. Third metal vias are formedon top of the recessed second gate contacts over the second gates,according to a third via pattern through the filling material and theupper layer down to the recessed second gate contacts. The third metalvias are taller than the first metal vias.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top-down view of a schematic for an integrated circuitaccording to one or more embodiments.

FIGS. 2A, 2B, and 2C are cross-sectional views of an intermediatestructure according to one or more embodiments.

FIGS. 3A, 3B, and 3C are cross-sectional views of the intermediatestructure depicting trench silicide (TS) contact formation according toone or more embodiments.

FIGS. 4A, 4B, and 4C are cross-sectional views of the intermediatestructure depicting deposition of an interlayer dielectric layeraccording to one or more embodiments.

FIGS. 5A, 5B, and 5C are cross-sectional views of the intermediatestructure depicting contact etching according to one or moreembodiments.

FIGS. 6A, 6B, and 6C are cross-sectional views of the intermediatestructure depicting gate contact patterning according to one or moreembodiments.

FIGS. 7A, 7B, and 7C are cross-sectional views of the intermediatestructure depicting further gate contact patterning to open a nitridelayer according to one or more embodiments.

FIGS. 8A, 8B, and 8C are cross-sectional views of the intermediatestructure depicting metallization of the source/drain (CA) contacts andgate (CB) contacts according to one or more embodiments.

FIGS. 9A, 9B, and 9C are cross-sectional views of the intermediatestructure depicting M0 metal patterning according to one or moreembodiments.

FIGS. 10A, 10B, and 10C are cross-sectional views of the intermediatestructure depicting further M0 metal patterning according to one or moreembodiments.

FIGS. 11A, 11B, and 11C are cross-sectional views of the intermediatestructure depicting metallization of the M0 metal layer according to oneor more embodiments.

FIGS. 12A, 12B, and 12C are cross-sectional views of the intermediatestructure depicting a block mask to open the merged CB (gate) contactaccording to one or more embodiments.

FIGS. 13A, 13B, and 13C are cross-sectional views of the intermediatestructure depicting recessing the metal layer (merged CB gate contact)according to one or more embodiments.

FIGS. 14A, 14B, and 14C are cross-sectional views of the intermediatestructure depicting removal of the organic planarizing layer andaddition of a filling material according to one or more embodiments.

FIGS. 15A, 15B, and 15C are cross-sectional views of the intermediatestructure depicting deposition of an upper layer according to one ormore embodiments.

FIGS. 16A, 16B, and 16C are cross-sectional views of the intermediatestructure depicting V0 metal patterns according to one or moreembodiments.

FIGS. 17A, 17B, and 17C are cross-sectional views of a final structureaccording to one or more embodiments.

FIGS. 18A and 18B together illustrate a flow chart of a method offorming an integrated circuit according to one or more embodiments.

DETAILED DESCRIPTION

Various embodiments are described herein with reference to the relateddrawings. Alternative embodiments may be devised without departing fromthe scope of this document. It is noted that various connections andpositional relationships (e.g., over, below, adjacent, etc.) are setforth between elements in the following description and in the drawings.These connections and/or positional relationships, unless specifiedotherwise, may be direct or indirect, and are not intended to belimiting in this respect. Accordingly, a coupling of entities may referto either a direct or an indirect coupling, and a positionalrelationship between entities may be a direct or indirect positionalrelationship. As an example of an indirect positional relationship,references to forming layer “A” over layer “B” include situations inwhich one or more intermediate layers (e.g., layer “C”) is between layer“A” and layer “B” as long as the relevant characteristics andfunctionalities of layer “A” and layer “B” are not substantially changedby the intermediate layer(s).

As aggressive scaling occurs, for 7 nanometer (nm) technology node andbelow, to pattern gate contacts (CB) and via contacts on dense gates,merged self-aligned CB contact (gate open (GO) mask) and mergedself-aligned V0 contact are needed. V0 refers to a metal via utilized asa contact.

However, for the middle-of-the-line (MOL) stack, there is a need toreduce the resistance between a source/drain (CA) contact and M0contact, and the state-of-the-art scheme results in a very tall V0 metallayer, which creates a lot of process challenges and risks (in thestate-of-the-art process). Also, introduction of the GO mask increasesthe mask count and thus increases the cost. To form the V0 metal layer,the state-of-the-art requires printing gate open (GO) contact for densegates with dense contacts (critical mask), GO contact etch andmetallization, additional interlayer dielectric deposition, printing CBcontact for normal gates (critical mask), and CB contact etch andmetallization.

Embodiments introduce a novel technique to form two-dimensionalself-aligned tall via V0 contacts, which mitigates the above issues.Embodiments provide a novel technique to form a gate contact (CB) andfully self-aligned via (V0), without using an additional gate open (GO)mask. As such, a merged gate contact metal recess process is introducedfollowed by silicon nitride (SiN) fill. Embodiments are configured todecrease the GO mask count (i.e., the critical mask) as compared to thestate-of-the-art.

One or more embodiments form short via (V0) contacts, and the short viacontacts connect to the M0 metal contact below and the M1 metal contact.The M0 metal contact is connected to a gate contact. In contrast to thestate-of-the-art, tall via (V0) contacts are formed in the SiN, and thetall via contacts individual connect gate contacts to the M1 metalcontacts. In one or more embodiments, tall via contacts are utilized tocontact the gate contacts without the M0 metal contact. The tall viacontacts are individually formed through the SiN after recessing thegate contacts, such that each gate contacts has its own tall viacontact. The tall via contacts are self-aligned to the both gatecontacts below and the M1 metal contacts above. Further details are seenin the figures.

FIG. 1 is a top-down view of a schematic for an integrated circuit 100according to one or more embodiments. The schematic of the integratedcircuits 100 depicts many layers that have been formed. Metal layer 1704is the (tall) V0 metal layer, which is a metal via. Reference can alsobe made to FIGS. 17A, 17B, and 17C as example cross-sectional viewsfurther illustrating the tall V0 metal layer 170 along with otherelements as described further herein.

FIG. 1 also illustrates a trench silicide (TS) contact 302 and a metallayer 804. The metal layer 804 is a source and/or drain contact (CA).The source/drain contact (CA) is on top of the TS contact. Metal layer1102 is an M0 metal layer. The M0 metal layer 1102 is on top of thesource/drain (CA) contact 302.

Metal layer 1714, 1716 is an M1 metal layer. The M1 metal layer 1714 ison top of the tall V0 metal layer 1704. The M1 metal layer 1716 is ontop of V0 metal layer 1706 (shown in the figures below).

Additionally, the integrated circuit 100 includes fins 220 and gates212. Also, 3 gate locations A, B, C are identified which correspond tothe gate locations A, B, C in FIG. 1. Portion 150 illustrates formationof part of the integrated circuit 100 (particularly 2 gates 212) in amanner that may not include some techniques of embodiments. The 2 gates212 illustrated in portion 150 are less dense than the gates 212 at gatelocations A, B, C. The gates 212 at gate locations A, B, C are densebecause of their small gate pitch. In one implementation, the gatedensity at portion 150 may be as dense as gates 212 at gate locations A,B, C; the only difference here is that in portion 212 at gate locationsA, B, C, there needs to be individual gate contacts and via contacts toconnect those gates. However, in portion 150, the two gates areconnected with a single common gate contact.

It should be appreciated that the integrated circuit 100 in FIG. 1 is aconceptual view and some details may not be explicitly shown in thelayout. FIGS. 2-17 illustrate a fabrication process to build anintegrated circuit, such as the integrated circuit 100, according to oneor more embodiments. FIG. 1 shows line X-X, line Y-Y, and line Z-Z. Thefabrication process for building the integrated circuit is illustratedfrom the perspective of cross-sectional views taken along the line X-X(FIGS. 2A-17A), line Y-Y (FIGS. 2B-17B), and line Z-Z (FIG. 2C-17B).

FIGS. 2A, 2B, and 2C are cross-sectional views of an intermediatestructure 200 (for an integrated circuit) according to one or moreembodiments. One or more fins 220 may be formed in a substrate 202 atdesired locations using standard lithography processes. The substrate202 may be a wafer, such as, e.g., a silicon wafer. The substrate mayalso include germanium, silicon germanium, etc.

One or more shallow trench isolations (STI) 204 are formed on thesubstrate 202 using standard lithography processes. The shallow trenchisolations 204 prevent electric current leakage between adjacentsemiconductor device components.

Source and drains 206 are formed in the substrate 202 using standardlithography processes. The sources and drains 206 may be p-type orn-type wells depending on the application, and the sources and drains206 have a corresponding epitaxy layer on top.

An interlayer dielectric (ILD) layer 214 is formed on top of the shallowtrench isolation areas 204 and on the top of the source and drains 206.The interlayer dielectric layer 214 may be an oxide layer. An example ofthe oxide layer 214 may be, e.g., silicon dioxide. In oneimplementation, the layer 214 may be flowable oxide, plasma-enhancedchemical vapor deposition (PECVD) oxide, etc.

Openings may be formed in the oxide layer 214 down to the substrate 202in preparation for gates 212. Gates 212 are formed on the substrate 202using standard lithography processes. The gates 212 may be high-κ metalgates. The gates 212 may include a high-κ material, such as, e.g.,hafnium dioxide (HfO₂), zirconium dioxide (ZrO₂), and titanium dioxide(TiO₂), with a metal on top. The gates 212 are formed over the fins 220as understood by one skilled in the art.

A layer 210 may be formed on top of the gates 212. The layer 210 may bea nitride, such as silicon nitride, siliconborocarbonitride (SiBCN),etc. Chemical mechanical polishing/planarization may be performed on theintermediate structure 200 to form a level surface.

FIGS. 3A, 3B, and 3C are cross-sectional views of the intermediatestructure 200 depicting trench silicide (TS) contact formation accordingto one or more embodiments. Portions of the oxide layer 214 have beenremoved above the sources and drains 206, e.g., according to a pattern(not shown). The oxide layer 214 may be removed by etching with anetchant designed to remove the oxide layer 214 but not the nitride layer210. Trench silicide (TS) contacts 302 are formed on top of the sourcesand drains 206, and CMP processing is performed to level and smooth thetop of the intermediate structure 200. The TS contacts 302 may include asilicide at the bottom and metallization material on top. The trenchsilicide contact 302 may include WSi₂, TiSi₂, NiSi, and CoSi₂. Oneexample of forming the trench silicide contact 302 may include forming ametal on top of the source/drain 206 and then heating the intermediatestructure 200 to form the trench silicide contact 302, and may includefurther filling the contact 302 with conductive metals such as tungsten(W) and cobalt (Co) and/or with liner or barrier metal liners such astitanium nitride (TiN).

FIGS. 4A, 4B, and 4C are cross-sectional views of the intermediatestructure 200 depicting deposition of another interlayer dielectriclayer 402 according to one or more embodiments. The interlayerdielectric layer 402 is formed on top of the nitride layer 210, theinterlayer dielectric layer 214, and the trench silicide contact 302using standard lithography processes. The interlayer dielectric layer402 may be an oxide layer. In one implementation, the material of theinterlayer dielectric layer 402 may be the same as layer 214. In oneimplementation, the layers 402, 214, and 204 may be or include the samematerial.

FIGS. 5A, 5B, and 5C are cross-sectional views of the intermediatestructure 200 depicting contact etching (CA) according to one or moreembodiments. A contact pattern/trench 502 is cut into the interlayerdielectric layer 402 of the intermediate structure 200 above the trenchsilicide contact 302. The contact trench 502 is etched in preparationfor source/drain contacts (CA contact).

FIGS. 6A, 6B, and 6C are cross-sectional views of the intermediatestructure 200 depicting gate contact patterning according to one or moreembodiments. For example, organic planarizing layer (OPL) 602 is formedon top of the interlayer dielectric layer 402. Patterns are etched inthe organic planarizing layer 602 and correspondingly etched into theinterlayer dielectric layer 402 as gate contact patterns 604 and 606.The gate contact patterns 604 and 606 expose the tops of the nitridelayer 210 (that cover the gates 212). The gate contact pattern 604 isfor a normal (CB) gate contact. The gate pattern 606 is for the mergedCB gate contact for 3 individual gates (or more than 3). The organicplanarizing layer 602 fills in the contact pattern/trench 502. Thisprocess is achieved by standard lithography processes.

Also, material of the organic planarizing layer 602 may be some otherhardmask material (e.g., TiN), which is formed by lithography patterningand pattern transfer, especially when multiple litho/etch processes areused. In one implementation, the organic planarizing layer 602 may bedeposited on the top surface of the intermediate structure 200, and theorganic planarizing layer 602 is etched into the desired shape.

In FIGS. 6A, 6B, and 6C, there is no need to utilize a separated gateopen (GO) mask. It should be appreciated that a block mask is to beutilized in FIGS. 12A-12C and 13A-13C as discussed below.

FIGS. 7A, 7B, and 7C are cross-sectional views of the intermediatestructure 200 depicting further gate contact patterning to open thesilicon nitride according to one or more embodiments. Gate contactpatterns 702A, 702B, 702C are formed in the nitride layer 210 to exposethe tops of the gates 212 in the merged CB contact pattern 606.Similarly, gate contact patterns 704 are formed in the nitride layer 210to expose the tops of the gates 212 in the normal CB gate pattern.

FIGS. 8A, 8B, and 8C are cross-sectional views of the intermediatestructure 200 depicting metallization of the source/drain (CA) contactsand gate (CB) contacts according to one or more embodiments. The organicplanarizing layer 602 is stripped off, and the metal layer is depositedon the intermediate structure 200 to fill the various trenches/patterns.For ease of understanding, the metal layer is designated as metal layers802, 804, and 806.

The metal layer 806 is formed on top of the gates 212 and nitride layer210 within the gate contact patterns 704 in pattern 604.

The metal layer 802 is formed on top of the gates 212 and nitride layer210 within the gate contact patterns 702A, 702B, 702C in pattern 606.

The metal layer 804 is formed on top of the trench silicide contact 302.The metal layer 804 may also be on top of portions of the nitride layer210 on the sides of the trench silicide contact 302.

The metal layers 802 and 806 are CB gate contacts. The metal layer 804is CA source/drain contacts. The metal layers 802, 804, and 806 mayinclude metals, e.g., such as cobalt (Co), tungsten (W), and copper(Cu), and may include metal liners such as Ti/TiN.

FIGS. 9A, 9B, and 9C are cross-sectional views of the intermediatestructure 200 depicting M0 metal patterning according to one or moreembodiments. For example, organic planarizing layer (OPL) 902 is formedon top of the interlayer dielectric layer 402. Patterns are etched inthe organic planarizing layer 602 such that the metal layers 804 and 806are exposed, all of which is in preparation for depositing the M0 metallayer. Also, the metal layer 802 remains covered because no M0 metallayer is to be deposited on the metal layer 802.

FIGS. 10A, 10B, and 10C are cross-sectional views of the intermediatestructure 200 depicting further M0 metal patterning to open theinterlayer dielectric layer and remove part of the gate contact and thesource/drain contact according to one or more embodiments. M0 metalpatterns 904 and 906 are formed in the interlayer dielectric layer 402and in upper portions of the metal layers 804 (CA source/drain contacts)and 806 (CB gate contacts). In preparation for depositing the M0 metallayer, M0 metal pattern 904 exposes the top of the metal layer 806 (CBgate contact), and M0 metal pattern 906 exposes the top of the metallayer 804 (CA source/drain contact). In one implementation, theinterlayer dielectric layer 402 may be oxide material and an oxide etchis performed to form the M0 metal patterns 904 and 906, along withetching the material (W, Co, and/or Cu) of the metal layers 804 and 806.The metal layer 802 (CB gate contact) remains covered by the organicplanarizing layer 902 and is thus protected.

FIGS. 11A, 11B, and 11C are cross-sectional views of the intermediatestructure 200 depicting M0 metallization of the M0 metal layer accordingto one or more embodiments. It can be seen that M0 metal layer 1102 isdeposited to fill the M0 metal pattern 906 (in FIG. 12) and that the M0metal layer 1104 is deposited to fill the M0 metal pattern 904. Chemicalmechanical polishing/planarization is performed to level the top surfaceof the intermediate structure 200.

FIGS. 12A, 12B, and 12C are cross-sectional views of the intermediatestructure 200 depicting a block mask to open the merged CB (gate)contact according to one or more embodiments. The block mask includesthe etched organic planarizing layer 1202 deposited on top of theintermediate structure 200 and etched into the pattern 1204. The pattern1204 exposes the tops of the metal layer 802 (CB gate contact), whileprotecting the M0 metal layers 1102 and 1104. The block mask of theorganic planarizing layer 1202 is cheaper (better) than a G0 mask andrequires fewer processing steps. Furthermore, the lithography processusing the block mask is cheaper because the block mask is a non-criticalmask. Being a non-critical mask means that the block mask cost will bemuch cheaper, the feature of the block mask is larger and shape issimpler, and the block mask does not need a lot of design effort andoptical proximity correction (OPC). Also, the processing cost ischeaper, because the block mask may be printed in older lithographytools, while the critical mask needs most advanced immersion tools, evenwith multiple patterning or extreme ultraviolet lithography (EUV) tool.

FIGS. 13A, 13B, and 13C are cross-sectional views of the intermediatestructure 200 depicting recessing the metal layer to form pattern 1304according one or more embodiments. Within the pattern 1204, the upperportion of the metal layer 802 is etched to only leave a short portionof the metal layer 802 above the gate 212 and nitride layer 210 in thepattern 1204. By recessing the metal layer 802 to thereby form pattern1304, each gate location A, B, C is separated (physically andelectrically) from one another such that the gates 212 are no longer(electrically) connected together by the metal layer 802; accordingly,each gate 212 in each gate location A, B, C has its own short portion(CB gate contact) of the metal layer 802. Although only 3 gate locationsA, B, C are shown for illustrative purposes, it should be appreciatedthat more than 3 gate locations may be generated according to thetechniques discussed herein.

FIGS. 14A, 14B, and 14C are cross-sectional views of the intermediatestructure 200 depicting removal of the organic planarizing layer 1202and addition of a filling material according to one or more embodiments.

The organic planarizing layer 1202 is stripped off and filling material1402 is deposited on the intermediate structure 200. The fillingmaterial 1402 fills the pattern 1304 and covers the respective shortportions of the metal layer 802. Also, the M0 metal layers 1102 and 1104are covered by the filling material 1402.

The filling material 1402 may be a nitride. In one implementation,examples of the filling material 1402 may include silicon nitride (SiN).The filling material 1402 is designed to be utilized to define the V0metal landing as discussed further below.

FIGS. 15A, 15B, and 15C are cross-sectional views of the intermediatestructure 200 depicting deposition of an upper layer according to one ormore embodiments. An upper layer 1502 is deposited on top of the fillingmaterial 1402. In one implementation, the upper layer 1502 may be a(ultra) low-k dielectric material.

In one case, low-k dielectric materials may include dielectric materialswith a dielectric constant k) lower than about 4.2.

FIGS. 16A, 16B, and 16C are cross-sectional views of the intermediatestructure 200 depicting V0 metal patterns (along with M1 metal patterns)according to one or more embodiments. V0 metal patterns 1602, 1604, and1606 are formed in the upper layer 1502 and the filling material 1402.

The V0 metal pattern 1602 includes trenches formed down to the M0 metallayer 1104. The V0 metal pattern 1602 is patterned for one-dimensionalself-aligned short V0 metal vias. The one-dimensional self-aligned viais self-aligned to top M1 line (self-aligned to M1 line minor axis)which is discussed below.

The V0 metal pattern 1604 includes trenches formed down to the metallayer 802. The V0 metal pattern 1604 is patterned to formtwo-dimensional self-aligned tall V0 metal vias. The two-dimensionalself-aligned via is self-aligned to both top M1 line (self-aligned to M1line minor axis), and also self-aligned to bottom CB line (self-alignedto merged CB line minor axis) as discussed below.

The V0 metal pattern 1606 includes trenches formed down to the M0 metallayer 1102.

FIGS. 17A, 17B, and 17C are cross-sectional views of a final structure1700 according to one or more embodiments. The final structure 1700 isan integrated circuit, such as, e.g., the integrated circuit 100.

Metal is deposited to fill in the patterns 1602, 1604, and 1606, therebyforming V0 metal vias with M1 metal layers on top.

For pattern 1602 exposing M0 metal layer 1104 (in FIGS. 16A-16C), thedeposited metal forms (short) V0 metal vias 1702 with an M1 metal layer712 on top. The V0 metal vias 1702 connect the M0 metal layer 1104 tothe M1 metal layer 1712.

For pattern 1604 exposing the short portions (CB gate contact) of themetal layer 802 (in FIGS. 16A-16C), the deposited metal forms (tall) V0metal vias 1704 with an M1 metal layer 1714 on top. The V0 metal vias1704 respectively connect each short portion of the metal layer 802(i.e., each CB gate contact) to an individual M1 metal layer 1714. TheV0 metal vias 1704 are self-aligned in two dimensions. For example, V0metal vias 1704 are self-aligned to both “across top metal direction” ofthe M1 metal layer 1714 and “across bottom metal direction” of the CBgate 802, thereby having alignment connecting bottom metal to topmetals.

In one implementation, the height of the (short) V0 metal layer 1702 mayrange from about 20-40 nanometers (nm). In one implementation, theheight of the (tall) V0 metal layer 1704 may range from about 60-100 nm.

For pattern 1606 exposing the M0 metal layer 1102 (in FIGS. 16A-16C),the deposited metal forms V0 metal vias 1706 with an M1 metal layer 1716on top. The V0 metal via 1706 connects the M0 metal layer 1102 to the M1metal layer 1716.

The M1 metal layer 1712, 1714, and 1716 is planarized via CMP to form alevel top surface and to remove excess metal of the M1 metal layer 1712,1714, 1716. The material of the metal forming the V0 metal layers 1702,1704, 1706 and M1 metal layers 1712, 1714, 1716 may include W, Co, Cu,etc.

FIGS. 18A and 18B together illustrate a flow chart of a method 1800 offorming contacts for semiconductor devices (which may be an integratedcircuit, such as, e.g., integrated circuit 100), according to one ormore embodiments. Reference can be made to FIGS. 1-17.

At block 1805, first gate contacts 806 are formed on top first gates212, second gate contacts 802 are formed on top of second gates 212, andterminal contacts (e.g., source/drain contacts 804) are formed on top oftrench silicide contacts 302, where the trench silicide contacts 302 areindividually formed on top of sources and drains 206. Examples aredepicted in FIGS. 8A-8C.

At block 1810, the first gate contacts 806 and the terminal contacts 804are recessed in order to form a first metal layer 1104, 1102 on top ofthe first gate contacts 806 and the terminal contacts 804. Examples aredepicted in FIGS. 10A-10C.

At block 1815, the second gate contacts 802 are recessed such thatrecessed second gate contacts 802 are separately on top of each of thesecond gates 212, where each of the recessed second gate contacts 802are separated from one another by a dielectric layer (e.g., interlayerdielectric layer 214). Examples are depicted in FIGS. 13A-13C.

At block 1820, a filling material 1402 is formed on top of the recessedsecond gate contacts 802 and the first metal layer 1102, 1104. At block1825, an upper layer 1502 is formed on top of the filling material 1402.Examples are depicted in FIGS. 14A-14C and 15A-15C.

At block 1830, a first via pattern 1602 is formed through the fillingmaterial 1402 and the upper layer 1502 down to first metal layer 1104 ontop of the first gate contacts 806, a second via pattern 1606 is formedthrough the filling material 1402 and the upper layer 1502 down to firstmetal layer 1102 on top of the terminal contacts 804, and third viapattern 1604 is formed through the filling material 1402 and the upperlayer 1502 down to the recessed second gate contacts 802.

At block 1835, in the first via pattern 1602, first metal vias 1702 areformed on top of the first metal layers 1104 over the first gatecontacts 806.

At block 1840, in the second via pattern 1606, second metal vias 1706are formed on top of first metal layer 1102 over the terminal contacts804.

At block 1845, in the third via pattern 1604, third metal vias 1704 areformed on top of the recessed second gate contacts 802 over the secondgates 212, where the third metal vias 1704 are taller than the firstmetal vias 1702. Examples are depicted in FIGS. 16A-16C and 17A-17C.

A height of the third metal vias 1704 corresponds to a thickness of thefilling material 1402. Each of the second gates 212 has side layers(layer 210) on sides of the second gates.

The recessed second gate contacts 802 are formed on top of the secondgates 212 along with the side layers 210. The side layers 210 includenitride.

The second gates 212 are formed at individual gate locations A, B, C.Recessing the second gate contacts causes the recessed second gatecontacts 802 to have a lower height than the dielectric layer 214 at theindividual gate locations A, B, C.

Each of third metal vias 1704 is formed on top of a separate one of therecessed second gate contacts 802 over the second gates 212, such thatthe second gates 212 at locations A, B, C are electrically separatedfrom one another.

A height of the third metal vias 1704 ranges from about 60-100nanometers. A height of the first metal vias 1702 ranges from about10-40 nanometers.

The sources and drains 206 include an epitaxy layer on top. The fillingmaterial includes nitride. The dielectric layer includes oxide.

A second metal layer 1712, 1714, 1716 is formed on top of the firstmetal vias 1702, the second metal vias 1706, and the third metal vias1704. The second metal layer 1712, 1714, 1716 includes at least one oftungsten, copper, and cobalt. The first, second, and third metal viasinclude at least one of tungsten, copper, and cobalt.

Technical effects and benefits include improved semiconductor devices,such as, e.g., integrated circuits, on a wafer. The improved integratedcircuit improves a computer processor. The technical effects furtherinclude forming tall via (V0) metal contacts in the semiconductor devicewithout using an additional gate open (GO) mask, which reducesprocessing steps and costs. A merged gate contact and metal recessprocess followed by filling material may be utilized to form the tallvia metal contacts.

It will be noted that various microelectronic device fabrication methodsmay be utilized to fabricate the components/elements discussed herein asunderstood by one skilled in the art. In semiconductor devicefabrication, the various processing steps fall into four generalcategories: deposition, removal, patterning, and modification ofelectrical properties.

Deposition is any process that grows, coats, or otherwise transfers amaterial onto the wafer. Available technologies include physical vapordeposition (PVD), chemical vapor deposition (CVD), electrochemicaldeposition (ECD), molecular beam epitaxy (MBE) and more recently, atomiclayer deposition (ALD) among others.

Removal is any process that removes material from the wafer: examplesinclude etch processes (either wet or dry), and chemical-mechanicalplanarization (CMP), etc.

Patterning is the shaping or altering of deposited materials, and isgenerally referred to as lithography. For example, in conventionallithography, the wafer is coated with a chemical called a photoresist;then, a machine called a stepper focuses, aligns, and moves a mask,exposing select portions of the wafer below to short wavelength light;the exposed regions are washed away by a developer solution. Afteretching or other processing, the remaining photoresist is removed.Patterning also includes electron-beam lithography.

Modification of electrical properties may include doping, such as dopingtransistor sources and drains, generally by diffusion and/or by ionimplantation. These doping processes are followed by furnace annealingor by rapid thermal annealing (RTA). Annealing serves to activate theimplanted dopants.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A method of forming contacts for a semiconductordevice, the method comprising: forming first gate contacts on top offirst gates, second gate contacts on top of second gates, and terminalcontacts on top of trench silicide contacts, wherein the trench silicidecontacts are individually formed on top of sources and drains; recessingthe first gate contacts and the terminal contacts in order to form ametal layer on top of the first gate contacts and the terminal contacts;recessing the second gate contacts such that recessed second gatecontacts are separately on top of each of the second gates, wherein eachof the recessed second gate contacts are separated from one another by adielectric layer; forming a filling material on top of the recessedsecond gate contacts and the metal layer; forming an upper layer on topof the filling material; forming first metal vias on top of the metallayer over the first gate contacts, according to a first via patternthrough the filling material and the upper layer down to the metal layeron top of the first gate contacts; forming second metal vias on top ofthe metal layer over the terminal contacts, according to a second viapattern through the filling material and the upper layer down to themetal layer on top of the terminal contacts; and forming third metalvias on top of the recessed second gate contacts over the second gates,according to a third via pattern through the filling material and theupper layer down to the recessed second gate contacts, the third metalvias being taller than the first metal vias.
 2. The method of claim 1,wherein a height of the third metal vias corresponds to a thickness ofthe filling material.
 3. The method of claim 1, wherein each of thesecond gates has side layers on sides of the second gates.
 4. The methodof claim 3, wherein the recessed second gate contacts are formed on topof the second gates along with the side layers.
 5. The method of claim4, wherein the side layers include nitride.
 6. The method of claim 1,wherein the second gates are formed at individual gate locations.
 7. Themethod of claim 6, wherein recessing the second gate contacts causes therecessed second gate contacts to have a lower height than the dielectriclayer at the individual gate locations.
 8. The method of claim 1,wherein each of third metal vias is formed on top of a separate one ofthe recessed second gate contacts over the second gates.
 9. The methodof claim 1, wherein a height of the third metal vias ranges from about60-100 nanometers.
 10. The method of claim 9, wherein a height of thefirst metal vias ranges from about 10-40 nanometers.
 11. The method ofclaim 1, wherein the sources and drains include an epitaxy layer. 12.The method of claim 1, wherein the filling material includes nitride;and wherein the dielectric layer includes oxide.
 13. The method of claim1, wherein another metal layer is formed on top of the first metal vias,the second metal vias, and the third metal vias; and wherein the anothermetal layer includes at least one of tungsten, copper, and cobalt. 14.The method of claim 1, wherein the first, second, and third metal viasinclude at least one of tungsten, copper, and cobalt.